Abstract
OBJECTIVES: To evaluate the associations between sleep disturbances and driving practices, including driving cessation and trajectories of daily driving mileage (change over time), in older drivers. DESIGN: Longitudinal. SETTING: New Haven, Connecticut. PARTICIPANTS: Four hundred thirty older drivers, mean age 78.5, recruited from clinic and community sites. MEASUREMENTS: Baseline measures included medical history, daily driving mileage, Insomnia Severity Index (ISI), Epworth Sleepiness Scale (ESS), and Sleep Apnea Clinical Score (SACS). Longitudinal outcomes included at least one episode of driving cessation and trajectories of miles driven per day, as recorded every 6 months over 2 years. RESULTS: At baseline, participants drove an average of 22.2 miles per day; 26.0% (112/430) had insomnia (ISI ≥ 8), 19.3% (83/430) had daytime drowsiness (ESS ≥ 10), and 19.9% (84/422) had high sleep apnea risk (SACS > 15). The sleep-based predictors of insomnia (risk ratio (RR) = 1.20, 95% confidence interval (CI) = 0.65-2.20), daytime drowsiness (RR = 0.94, 95% CI = 0.46-1.95), and high sleep apnea risk (RR = 0.62, 95% CI = 0.27-1.42) did not confer a significantly greater risk of driving cessation. Insomnia was the only sleep-based predictor that conferred a significant change in driving mileage, yielding an average decrease of 4.5 miles per day over 2 years (P = .01). In the insomnia model, covariates that were associated with less driving mileage were polypharmacy (≥ 4 medications) and each year of additional age, yielding an average decrease of 8.3 (P = .01) and 0.4 miles per day (P = .02), respectively, over 2 years. CONCLUSION: In a cohort of older drivers, insomnia and the covariates of polypharmacy and advancing age were longitudinally associated with less daily driving mileage. Because reductions in driving mileage in older persons often occur in response to reductions in driving capacity, these results support a clinical approach that considers insomnia-based cognitive-behavioral therapy and reduced polypharmacy as strategies for improving driving capacity in older persons.